1. Field of the Invention
The present invention relates to a controller of a power converter with adjustable jitter amplitude and a method of generating adjustable jitter amplitude thereof, and particularly to a controller of a power converter and a method of generating adjustable jitter amplitude thereof that can utilize a logic circuit of the controller to jitter a feedback voltage of a secondary side of the power converter or a current flowing through a primary side of the power converter to adjust turning-on time of a power switch of the power converter.
2. Description of the Prior Art
Currently, most consumer electronic devices adopt switching power supplies as power supplies, where the switching power supply can control an inductor included thereof to store/release power by switching a power switch included thereof to provide power matching specification requirements. If switching of the power switch is always maintained at specific frequency, an electromagnetic wave with the specific frequency can be easily radiated through connections among the consumer electronic devices, resulting in the consumer electronic devices suffering electromagnetic interference.
The prior art makes a switching frequency of the power switch jitter around the specific frequency (that is, frequency jittering) to solve the electromagnetic interference. The frequency jittering mainly jitters a fundamental frequency and a second harmonic of the power switch to execute power dispersion in a frequency domain to reduce peak power of the electromagnetic interference.
In a quasi resonant pulse width modulation mode, the quasi resonant pulse width modulation mode can naturally jitter between a first trough and a second trough to generate a jitter-like phenomenon. But, the jitter-like phenomenon can not significantly reduce the electromagnetic interference. In addition, when the quasi resonant pulse width modulation mode has a low voltage and heavy load, peak power of the electromagnetic interference is very large. For example, when a pulse width modulation frequency is between 150 KHz and 1 MHz, the peak power of the electromagnetic interference is very large.